Temperature measuring instrument



March 20, 1945. R. l. BRADLEY TEMPERATURE MEASURING INSTRUMENT OriginalFilec} July 1, 1941 m ill/rill E .l

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Patented Mar. 20, 1945 TEMPERATURE 2,311,603,, i MEASURING INSTRUMENTRobert I Bradley, Belmont, Mass. Original application July 1, 1941;Serial 'No.

400,676. Divided and this 1942, Serial No.449,413 r soiaims; (c1.73-367) This application isa division of myapplication which resulted inPatent No. 2,313,459, dated May 4, 1943, and isdirected to adifierentiorm of construction of a temperature measuring instrument fromthatclaimed in said patent, and having certain advantages thereover andnovel features distinguishing it therefrom.

In the drawing:

Fig. 1 isa front elevation of a preferrediorm of the instrumentembodying the present invention; I 1

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 a similar section, partly broken away, and on an enlarged scale;

Fig. 4 is a vertical section on the line 1-4 of Fig. 3 showing thetemperature-responsive element and the casingwhich houses it;

Fig. 5 is a section in'a planesimilarto Fig. 2,

illustrating, a modified construction;

Fig. 6 is a similar view showing another modification;

Fig. 7 a similar, fragmentary sectional view of the same construction asinFig. 6, n an enlarged scale, with the coil tion; and I e Fig. 8 is arear elevation of the coil supporting element shown in Fig. 2.

As here illustrated the instrument comprises a shallow saucer-likeconcave-convex circular base portion I which may be ofglass, plastic orother appropriate material, preferably transparent or translucent. Theouter edge 2 of this base is designed to engage a flat surface, forinstance the outer side of a window pane (not shown) and is preferablyflat to facilitate the attachment of the base to the support, for examleby cement. 3

In accordance with the present'invention, the temperature-responsiveunit is arranged at the outer, rear, or convex side 3 of the base and isprotected by an enclosing housing. This housing, as illustrated in Figs.2 and 3, comprises a substantially cylindrical annular flange 4 coaxialwith the base I and integrally joined tothe latter (although it maybe aseparate element if desired) and a removablecap or cover of'any" 3suitable material, for instance glass, plastic or metal and which, asillustrated, comprises a cylindrical side wall which telescopes snuglyover the flange 4. The flange 4, in cooperation with this removable cap5,-provides a chamber within which the temperature-responsiveunit ishoused and protected from mechanical injury; prefer ably the outer orrear wall of the cap 5 is furnished with slots [2 and louvers-l3 so thatthe and its mount in secapplication July 2,

temperature-responsive element may be fully exposed to the temperatureof the air at the outer or rear side of the instrument. 7 The base"! isprovided with a circular scale coaxial with the base and includingspaced gradnations 1 and designating numerals 8, and, if the base is oftransparent or translucentmaterial,

upon a support carried directly by the base I.

For this purpose the base I is provided with a post or stud m,preferably of the same material as the base and as here shown integralwith the base, this post or stud being in the nature of an annular,rearwardly directed cylindrical flange concentric with an aperture II atthe center of the base, said aperture being designed for the passage, ofthe pointer staff as hereafter described.

' The temperature-responsive unit 6 is an;

metallic flat spiral coil havingits outer end fixed in aslot IS in arearwardly directed ear l6 (Figs. 4 and 8) at the outer end of a radialarm carried by a split resilient clamping or gripping ring ll.

This ring l1, preferably of metal, is of such an internal diameter asfrictionally to grip the outer peripheral surface of the post or studIll so as normally to remain in adjusted position, although it iscapable of being turned angularly about the axis of the stud l0 ifsuflicientforce'be applied, thereby to permit calibration ofthe instrutothe inner end of the staff, making an angle of approximately with thestafi at the point of junction. This integral connection of the pointerto the bi-metallic coil provides great accuracy of operation, sincethere is no possibility of lost motionbetween the pointer and themovable inner end of the coil. As illustrated in Figs.,2 and.

3, the pointer I9 is curved substantially concentrically with theconcavity of the base I, and the staff which carries the pointer I9 isof such length that the pointer is spaced slightly from the front,inner, or concave surface of the base so as not to contact the base asit swings along the scale.

In Fig. 5, the coil chamber is defined by a forwardly directed integralportion of the base proper and the ring I? with the coil unit 6 iscarried by a boss Illa on the rear or outer wall of the coil housinchamber. jThe chambertmay have an inner wall [811 if desired.

As illustrated in Fig. 6, the coil is housed in a shallow box having acylindrical side Wall and a fiat front wall, the lattterrhe l wroyidedwith a central aperture. This box is secured to the base by means of ahollow stud--or postttl which passes through the centrahaperturetll \Ofthe base. A nut 22 engages .sc-rew threads on the,forward or inner endof the stud 2|, and thus clamps the box firmly against the -rear orconvex side of the base. A coil supporting ring l1, dike thatof :Fig.8,'embraces .the {rear -end -.of the-studfl and the peintertstaiipassesthrough the bore in the stud 2| -;and through the nut :22.

"I-I he .temperature; responsive coil unit ,mounted at its souter =end@as..shown and described, and with its inneraend rfashioned into a,pointer, has several ,advantages; ::f0l one, .it is {a much Simplified.form. .Inithis construction itwill .bemoted there need be no bearing.for the .swinging -,a-rm or ,pointer, which is. an advantage,eliminating possible frictional and corrosiontrpuble with the necessitytofroiling, which is usually :necessaryiin delicately econstructedinstruments of @any for the; purpose of iobtaining accurate iresults.

I Theobvious advantages ;of this tyne ,of =,instrument are ,that it isrompact, of simple and :reliable adesigri, inexpensive to manufacture,,and, because .of :its construction, may .be manufactured E'SD :thatritmay be :mounted .in spaces impractical ,for ;-any other type ofinstrument, thecauseit mayabe made .wafer thin, aSait has beendescribed.

The use of a temperature responsive coil-so fashionedthat.it.also.becomestthe complete WOI-king.mechanism, includingthe,pointer allowsjor economicahmanufacture, -and.- alsogbecause-cf ,theelimination of.saccessory parts, errors -:from :friction weight etc areeliminated. I

hnouts'tanding advantagetalso-tls the tact that after, a period of timethere :is :no effect tfrom corrosion on working ,parts,;as iis the casewhen bearings ,and. leversare-used.

This instrument .-.is ,practical ifonmquntings, sucheas .might :be-.reguired,- or attractive fqr, indo,or-desk,=table,ortwallrthermometers. .Itdsza-ISQ highly desirable for use on or nearwindowsz to ferences, together with compensation to offset for houseradiation, allows for the manufacture of an instrument for outdoormounting that will give more accurate temperature readings than isotherwise possible with any other type of instrument.

The foregoing device embodies simplicity of design, economy inconstruction, and sensitiveness andtaccuracy tint-operation.

Myinvention is'not limited to the precise construction shown herein, butmay be modified in '-many details, without departing from the spirit iofzthfi rclaims and within the scope thereof.

record outside temperaturefland: may .beaused ;on v

the inside ,or outside of rautomobiles, railtplanes, or. other .vehiclessimilarly.

,In theoutdoor: models, although the-,bhmetalliccoil is partially;insulated, from-the windownhy its housing, it :may ,in :some instances,-,sti1l the aiTectedby-heat loss or cold leakage throughathe window.,This, '.0fCOU.1=Se,;iS-t1'1leiOfaI1Y outside thermometer. mounted;close to ;a:buildin-g. ;However, ,the .bi-metallic coil 7 in 1 thisthermometer is preferably. made: slightly over-active= or :sensitive tocompensate A for average heat d055,! by making the...coil longer.than-usual, andrit being cumulativewith increased, temperature change;it. isapossible and .practicalto, offset the. higher; percentage ofheat,loss or cold leakage-if ,thebuilding is.air..conditioned,-.asthe.differentialbetween outside -.and in side,temperature,increases.-'1herefore, elimination .of frictional sand vweight: inter-- I claim:

*1. Athermometer having a case including a hollow oncavcgconvcx baseportion providing a ishallowrchamherztor the reception of a pointer,fithe edgerofwtheibase portion being fiat and designed ,to engage a flatsupporting surface, the basehaving a central aperture, a pointer curvedsubstantially to conierm tuth zcurvatur .Q "'th concave $81616 59 thebase. 1 3.9 winter havin -;a integral :staff pcrticn -=,e.xten.di.ns axal h u h the aperture in the bas :t tt e convex :sid of the ,latter, .abimetallic (coil having its :inner end integral with ,said stafi, the{coil being disposed at the convex @sidaof athe :base, mean normallyholding the outer end of the coil;in fixed;po sit on, andmeans,previding-a housing o t z .-2. .-A thermometer aha-ring .a cas in inghollow concavo-convex base portion providing ,a shallow chamber,mnthemeception of :a pointer, theTedgebnthe :base portion being hat anddesigned directly to engage ,a,flat,supp,orting,surface, ,the ,base,having i-azcentral aperture, ta ino mallyfixed -annnlusi-coa ial with ad openin in the base andzqdisposed-atethe .convex ,side ,of ,the base abimetallic coil disposedgattheiconvex side of the base,a,-,-plit-;co1lar frictionally embracing the annulus wand ihaving =-asubstantially radial arm, means uniting the outer end of thetcoil tothegoutemendr ortiontof;said arm, the, inneriend portion ofithecoilzbein .s ane nform araoint staff and -.ext.ending,axia ly th ou thnqnenin in the base to the concave side of the latter, the stair havinan integral portion whi h nonst tutes-a pointer, the pointer zbeingdisposed at theconcave sidetofithe basegand the r asezhavingmdnationshcoouerable with rthe ,pointer ,-to :indicateztemperatu-revariations.

A th mome er shaving :a :case inc udin :a unitary llow eoncav econvcxhas nortionzh ins a central i-aperture laud :a-substantiall ;plaifor-ward .ed -e designed :fo rcc tact with assurport, mousin means R at[the convex as d of :th base d fin n in cham e fo :th r e epticn iii :athermally responsive element, a fixed gann ilar stud within said=chamber .and carr ed da rth bafiiia normally stationa yrsplitaco laembra n stud, ,thcollarsbeingmanuallyrotatabl relatively rtothesstudrandih vin ra Substantially fi mma bimetalrlic=coil havingitsouter end fixed to :saidarm laud-havin ritsinne cendnortiona raedaaxiallynftthetco. ttoform-za-niinde stafftwhicheextendslthmugh,theaaperture ipgthe base, an-iindex arm int gralvwith-asaid staff n which makessan,an leicfrapnroximate yq :w-ith thestafiaatiits, oint .of,j-unctionwith the; latter, theireeomen-portionQfssa-id arm bcin nurved concentrically -.with th conc ve tsurface :ofhe bas ,the .index. staff being (o :suc ;-len t -z h the ,index arm.isasna edaassli ht :distanc rtrcm therinnerrconcavetsurtaoaof thabase;

14... Arthermomekna tfie i fi it n 39133 further characterized 2111 1that the :housin means tional engagement with saidfiange.

5. A thermometer as set forth in claim 1 further characterized in thatvthe housing means comprises a rearwardly directed hollow boss hav l ingsubstantially cylindrical side walls integral with the base and whoserear wall is integral with its sidewalls, the means which normally holdsthe outer end of the coil in fixed position com- 1 prising a stud whichprojects forwardly from the rear wall of the hollow boss t 6. Athermometer asset forth in claim 1 fur ther characterized in that thehousing means" comprises a substantially cylindrical box includ 'ing aside wall and a front Wall, the front wall passing through said apertureand through a corresponding aperture in the base, the studjhaving afixedhead at its rear end andscrewthreads at its forward end engaged bya IllltWhiCh bears against the inner concave surface of the base,

thereby clamping the box to the base, and a cover frictionally ens forthe box having a rim which gages the wall of the box.

7. A thermometer asset forth in claim 1 furq ther characterized in thatthe base is circular and of spherical curvature.

8. A thermometer as setforth in claim 1 further characterized in thatthe base is transparent and in having the graduations soarranged as tobe readable from the convex side of the base.

ROBERT I. BRADLEY.

having a central aperture and an annular stud

